In many conventional gasoline engines, particularly those used in automotive applications, a carburetor mounted atop an intake manifold forms a principle component of a fuel system. As is well known, combustion air is drawn through the carburetor. A controlled amount of gasoline is added to the incoming air to form a combustible fuel/air mixture, as the air passes through a venturi throat formed in the carburetor. The intake manifold, which includes passages that communicate with valve controlled intake ports in the cylinder head of the engine, conveys and distributes the fuel/air mixture from the carburetor to the combustion chambers.
In theory, the liquid gasoline is vaporized prior to entering the combustion chambers. In a typical IC engine application, however, a portion of the gasoline remains unvaporized and in a liquid state even as it enters the combustion chamber, finally vaporizing during the combustion process. The presence of unvaporized fuel in the combustion chamber reduces the heat of combustion, thus limiting the power output of the engine. In the parent case an apparatus and method for operating an internal combustion engine is disclosed. The illustrated apparatus and described method provides a means for recovering a substantial amount of heat which in more conventional IC engines is exhausted as waste. This recovered heat is used to vaporize the liquid fuel and to superheat the fuel/air mixture. The illustrated apparatus includes a fuel introducing device such as a carburetor, a vaporizer for at least partially vaporizing the liquid fuel discharged by the carburetor and a fuel mixture heater for heating the fuel/air mixture prior to introduction into combustion chambers. An exhaust driven homogenizer is disposed in the fuel mixture flow path intermediate the vaporizer and the fuel mixture heater. The homogenizer is operative to thoroughly mix and homogenize the mixture and also pressurizes and adds additonal heat to it.
As disclosed in the parent case, the fuel vaporizer comprises a housing defining an internal chamber. The walls of the housing includes passages through which engine coolant is passed in order to heat the enclosed chamber. In operation, heat from the coolant is transferred via the chamber walls to the fuel passing through the chamber. The disclosed construction works satisfactorily; however, improvements in the heating efficiency and overall performance are always desired. For example, it is believed that after engine shutdown, as the vaporizer chamber cools, any vaporized fuel in the flow path condenses and collects at the base of the chamber. Upon startup, the collected fuel appears to be immediately ingested by the engine and may cause an overrich running condition for a time which is undesirable.